textproduct: Quad Cities

KEY MESSAGES

- Seasonable temperatures, dry conditions, and some hazy skies today.

- Widespread showers and thunderstorms likely Friday. There is an 80-90% chance of rainfall amounts over 1" and a 40-70% chance of rainfall amounts over 2".

- Isolated strong to severe thunderstorms may be possible in southeast Iowa, northeast Missouri, and west-central Illinois Friday afternoon. SPC has issued a Marginal (level 1 of 5) risk of severe thunderstorms.

SHORT TERM /THROUGH TONIGHT/

Issued at 235 AM CDT Thu Jul 30 2026

Water vapor imagery this morning denotes a mid-level ridge across the western CONUS and a trough to the east. Beneath the trough, high pressure sits over northern Illinois, which will shape much of the forecast today and tonight. Meanwhile, a shortwave currently over southwest Wyoming will arrive late tonight into early Friday morning, bringing our next chance for rain.

Today, as we remain under the influence of high pressure, yet another dry and seasonable late July day is in store. With high pressure just to our east, skies will be clear save for some high cirrus and low concentrations of dispersing wildfire smoke aloft. This should have a negligible impact on diurnal heating, allowing temperatures to rise into the mid to upper 80s.

By tonight, high pressure will shift southeastward as the shortwave progresses along the northern periphery of the ridge. This will support the development of a surface low over eastern Nebraska into western Iowa. Ahead of this low, moisture advection will increase with PWATs of 1.8-2.2 inches streaming in from the southwest. This is well above the 90th percentile of PWATs for late July (1.7 in), but falls within the common time of year for PWATs to be maximized. This ample moisture will set the stage for a widespread rain event on Friday.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 235 AM CDT Thu Jul 30 2026

Friday through Saturday... As the shortwave moves east- southeast across Iowa, showers and thunderstorms will develop along the nose of the LLJ in western and central Iowa, reaching the western edge of the CWA by 10-12Z. Marginal instability of up to 500 J/kg of MUCAPE will support embedded storms within the showers, especially south of Interstate 80, through the morning. The potential for any severe storms will be limited through the morning due to to weak instability. Come afternoon, some clearing across southeast Iowa, northeast Missouri, and west- central Illinois will help increase MUCAPE to 1000-1500 J/kg. This, combined with 0-6km shear of 30-35 kts, could support isolated strong to severe thunderstorms Friday afternoon with the primary threats being localized damaging winds and isolated tornadoes.

Showers and storms will continue overnight Friday into Saturday. This system will be slow to exit the area, resulting in lingering showers through Saturday morning to afternoon. Given the ample moisture available, rainfall accumulations continue to trend upwards. At least 1 inch of rain is highly likely (NBM 80-90%), and the chances of 2 inches or more from the NBM are now at 40-70% from southwest to northeast. This will be quite welcome due to the recent dry conditions, though heavy rain rates over a short period could result in localized flooding concerns, especially in urban areas.

Lastly, as the shortwave departs Saturday, a tight pressure gradient will cause gusty winds up to 30 mph through the evening.

Sunday through Thursday... Following the passage of the shortwave, a ridge will briefly take hold over the region before the flow aloft becomes more zonal. Of note is a deep trough over southern Canada through much of next week, which will send impulses through the flow and provide multiple chances for rainfall.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 545 AM CDT Thu Jul 30 2026

High pressure in control will result in prevailing VFR today into tonight with a continuation of light winds. An approaching storm system may spread showers and embedded thunderstorms into eastern Iowa late in this TAF period. Have low confidence on coverage and exact timing of any rain this far out, so have mentioned showers in a PROB30 at CID for now.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.